Analysis of the weight loss during sintering of silicon-carbide whisker-reinforced alumina composites

Good densification of Al2O3-SiC whisker composites usually requires use of the expensive hot-pressing technique. In this work, composites with 12 vol% whisker content have been made by pressureless sintering at temperatures above 1700 degrees C. To evaluate the effect of the sintering environment, tests were conducted either with samples placed in different powder beds, or by gas pressure sintering. The highest densities are obtained by the use of an alumina powder bed, or by gas pressure sintering. The latter method leads to densities of 95% of theoretical. The densities achieved are strongly dependent on the chemical stability of the species at the sintering temperature. This stability was evaluated by measuring the weight loss after sintering. Then, an analysis of the sintering process with reference to chemical engineering techniques was conducted. The analysis shows the relevance of the selected sintering cycles. (C) 1997. Published by Elsevier Science Limited. All rights reserved.